PHP in templates: Pain or Pleasure

PHP in templates: Pain or Pleasure? Probing ExpressionEngine’s Parse Order EECI2010, June 2nd, San Francisco, USA

Hi! I’m Low! Lodewijk Schutte @low

ExpressionEngine Templates - Take care of the design - Contain logic to display content - Logic consists of tags, variables and conditionals - Are parsed by EE’s Template Parser in a certain order

Template logic Tags - Plugin and Module tags - Single: !"#$%&"'()*%+",-.(/&0 - Pair: !"#$%)*'11"2%"13(4"&056665!7"#$%)*'11"2%"13(4"&0 - Contain tag variables

Template logic Global Variables - Parsed early: !&"89"13:;05!"9<"/%9,:='(05!&14$$"30 - Parsed late: !$'3*>66605!)*'(&"305!&)(""1:1'9"0 - Usually a simple string replace, so lightweight

Template logic Conditionals - Simple, parsed early: !4?5&"89"13:;056665!74?0 !4?5"9<"/%9,:='(5>>5@)*""&"@056665!74?0 !4?5&14$$"35A>5@$4)+2"&@056665!74?0 - Advanced, parsed late: !4?5&)(""1:1'9"5>>5@B."@056665!74?0 !4?5&"89"13:;5>>5@@056665!4?%"2&"056665!74?0 !4?5&"89"13:;5A>5@@5CDE53'8:='(5A>5@3.9'3.@0 55666 !74?0

http://icanhaz.com/parse-order

EE’s Parse Order 1. Snippets, global-, segment- and embed variables 2. PHP on Input 3. Segment-, embed- & global simple conditionals 4. Preload replace variables 5. Module and plugin tags 6. PHP on Output 7. Advanced conditionals 8. Embedded templates 9. Other variables

Will work: !"#$%)*'11"2%"13(4"& 5 )*'11"2>F1"-&F 5 &3'3G&>F.$"1!4?5&"89"13:;5>>5@'22@0H?"'3G("/!74?0F 5 /,1'94)>F1.F0 5 !"##$%&'($)*&+($##, !7"#$%)*'11"2%"13(4"&0

Won’t work: !"#$%)*'11"2%"13(4"& 5 )*'11"2>F1"-&F 5 &3'3G&>F.$"1!4?59"9<"(:8(.G$5>>5@I@0H?"'3G("/!74?0F 5 /,1'94)>F1.F0 5 !"##$%&'($)*&+($##, !7"#$%)*'11"2%"13(4"&0

#5: "#$-tag processing - Tags at root level are parsed, rinse, repeat - Plugin tags look inside for other tags and parse those ﬁrst, recursively - This order can be reversed with $'(&">F41-'(/F on any plugin tag

Low Variables Parse at stage #1, #5 or #9. You choose!

Low Variables example Name Type Early parsing !&*.-:-'(14180 Checkbox Yes !-'(1418:9"&&'8"0 Text input No !-'(1418:2"="20 Radio group No

Low Variables example

Low Variables example !4?5&*.-:-'(14185>>5@,@0 J/4=5)2'&&>F-'(141852"="2K!-'(1418:2"="20FL J*;LM'(1418AJ7*;L !"#$%3"#342"0 555!"#$%2.-:='(4'<2"&%$'(&"5='(>F-'(1418:9"&&'8"F0 !7"#$%3"#342"0 J7/4=L !74?0

Low Variables example J/4=5)2'&&>F-'(141852"="2K!-'(1418:2"="20FL J*;LM'(1418AJ7*;L !"#$%3"#342"0 555!"#$%2.-:='(4'<2"&%$'(&"5='(>F-'(1418:9"&&'8"F0 !7"#$%3"#342"0 J7/4=L

Low Variables example J/4=5)2'&&>F-'(141852"="2K!-'(1418:2"="20FL J*;LM'(1418AJ7*;L !"#$%3"#342"0 555N..+5<"*41/5,.GO5'5!-'(1418:2"="20K*"'/"/59.1+",A !7"#$%3"#342"0 J7/4=L

Low Variables example J/4=5)2'&&>F-'(141852"="2K!-'(1418:2"="20FL J*;LM'(1418AJ7*;L J$L 555N..+5<"*41/5,.GO5'5!-'(1418:2"="20K*"'/"/59.1+",A J7$L J7/4=L

Low Variables example J/4=5)2'&&>F-'(141852"="2K3*(""FL J*;LM'(1418AJ7*;L J$L 555N..+5<"*41/5,.GO5'53*(""K*"'/"/59.1+",A J7$L J7/4=L

Low Variables For EE 1.6.8+ and EE 2.0.2+ Get it now at loweblog.com or devot-ee.com

embed advanced conditionals "#$-tags segment variables embed user deﬁned global variables

Input Output P$*$ !"#$0 !"#$0 P$*$ J*392L J*392L

Why (not) use PHP? Pros Cons Can increase performance Might need to disable caching Extend EE without add-ons Possible security issues Speciﬁc customization More control and ﬂexibility

Some best practices - Assistance: save templates as ﬁles, use editor, read docs - Clarity: logic ﬁrst, parse variables later - Readability: use alternative syntax - Security: never assume

Example #1 - Idea: better advanced conditionals - Problem: EE still parses code in advanced conditionals, which impacts performance - Solution: use PHP on input to handle conditionals, thus only generating EE code that should be parsed

Example #2 - Idea: fully hackable URL for news channel - Problem: superﬂuous segment, the template name - Solution: use PHP in index to select the right embed

Example #3 - Idea: show channel entries with title beginning with X - Problem: !"#$%)*'11"2%"13(4"&0 tag cannot do this out of the box - Solution: use PHP on input to get entry_ids and feed those to the !"#$%)*'11"2%"13(4"&0 tag

Example #4 - Idea: track where 404s are coming from - Problem: cannot do this out of the box or without third party software - Solution: hijack Referrer module and use PHP in the 404 template to add records to the database

Example #5 - Idea: show banners in between blog posts (post, banner, post, post, banner, post, post, banner...) - Problem: cannot do this elegantly out of the box - Solution: use PHP on output to store banners in array and display them at the right position

Example #6 - Idea: customized RSS feed - Problem: cumbersome if not impossible out of the box - Solution part 1: use PHP on input to catch form and generate a custom URL - Solution part 2: use PHP on input to read segments and set parameters in RSS feed

Questions?

Look for slides at slideshare.net/lodewijkschutte http://www.flickr.com/photos/thebees/3412843560/ http://www.flickr.com/photos/arne-list/2934797540/ http://www.flickr.com/photos/abennett96/3625684918/ http://www.flickr.com/photos/goopymart/291244864/

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PHP in templates: Pain or Pleasure

by Lodewijk Schutte on Jun 04, 2010

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